Front Range winters demand a dependable furnace. When a gas furnace won’t light, the problem often traces back to a struggling igniter. In Denver, with its dry air, frequent freeze-thaw cycles, and occasional voltage swings, igniter failures show up at the worst times. I’ve seen homeowners replace filters religiously and still wake to a cold house because a $40 part quit. The fix may be simple, or it may expose deeper issues in the ignition and safety chain. Knowing how to diagnose the igniter and the parts that work around it can save a service call, or at least help you talk intelligently with a tech during an urgent visit.
This guide focuses on the real-world patterns: what fails, why, how to troubleshoot without getting in over your head, and when to pivot from gas furnace repair https://reidzegb271.image-perth.org/furnace-installation-denver-co-choosing-gas-vs-electric Denver calls to broader solutions like upgrades or even full replacements. I’ll use practical details from field experience and the realities of permits, altitude, and Denver’s aging housing stock.
How a modern furnace lights, and where the igniter fits
Most residential gas furnaces in Denver built since the late 1990s use hot surface ignition. Think of a small ceramic finger, glowing orange when energized, that lights the gas stream from the burners. Older units may use intermittent pilot or standing pilot systems, but in rental-heavy neighborhoods and post-2000 builds, hot surface igniters are common.
The ignition sequence is choreographed:
- The thermostat calls for heat, signaling the control board. The inducer motor starts to clear the heat exchanger and prove draft. The pressure switch verifies airflow. The igniter energizes and glows for a set time, usually 15 to 30 seconds. The gas valve opens, burners ignite, flame sensor proves flame. The blower starts after a short delay to move warm air.
If the igniter doesn’t glow, or it glows but the burners fail to light, the furnace will shut itself down. After a few tries, it will lock out for safety. The LED on the control board will often flash a code, which tells you where to look first.
Why igniters fail more in Denver
Altitude and climate matter. At 5,280 feet, air density changes combustion behavior. Manufacturers derate furnaces for altitude because less oxygen affects flame characteristics. When furnaces run lean or draft conditions are marginal, ignition cycles can be longer or more frequent, which stresses igniters. Dry air and dust accumulation, common in Denver homes due to evaporative summers and construction dust from steady development, coat the igniter surface and burners, making reliable ignition harder.
Voltage fluctuations are another culprit. In older neighborhoods with shared transformers or big draw events, you can see dips that stress ceramic igniters. I’ve measured 110 to 127 volts on the same block across a day. That swing speeds up thermal fatigue. Add in frequent cycling on shoulder-season days, and igniters crack or glaze sooner.
The last factor is handling. Hot surface igniters are fragile. Touching the gray silicon carbide element with bare fingers can leave skin oils that create hot spots and reduce life. A weekend filter change can turn into a broken igniter if someone bumps it.
Recognizing an igniter issue versus other ignition problems
People often assume any no-heat situation is an igniter. Sometimes they’re right. Other times the igniter is fine but the sequence fails upstream or downstream. Symptoms help you aim.
If the thermostat calls for heat and you hear the inducer motor start but never see the orange glow through the view window, suspect the igniter or its power circuit. If you see the glow but hear a click with no flame, look at the gas valve, gas supply, or burners. If the burners light then shut off after a second or two, the flame sensor may be dirty. A furnace that tries three times and locks out could be any of these, so watch the sequence if you can.
Denver homeowners often see a draft-induced pause, a faint humming, then silence. Many have learned to check the small observation port. That glimpse of orange is your first answer.
Safe, simple checks a homeowner can do
Some steps are safe, others demand caution. If you smell gas, shut things down and call a pro. If you are comfortable with basic checks, a few actions can prove useful without risking injury or damaging parts.
Here is a short, careful sequence that balances safety and useful information.
- Confirm power and settings. Set the thermostat above room temperature and switch the fan to Auto. Verify the furnace switch near the unit is on, and check the breaker. Low-voltage thermostat wires sometimes get knocked loose by storage boxes. Watch and listen. Remove the small furnace door panel if there is a view port, or use the sight glass. Note if the inducer starts. See if the igniter glows. Count the seconds between steps. Write down any blinking LED code on the control board. Check the filter and return air. A clogged filter can affect temperature in the cabinet and lead to hard starts. Replace a filthy filter and reseat the door, which often holds the safety switch closed. Inspect the igniter visually. With power off and the furnace cool, look at the igniter for chips, cracks, or a chalky white coating. Do not touch the element. Loose connections or a brittle wire jacket are red flags. Reset once. Some control boards allow a simple power cycle to clear lockout. Turn off the furnace power for 60 seconds, then restore. Do not repeatedly cycle if you smell gas or hear repeated clicking without ignition.
If you see no glow and the igniter looks damaged, that’s a strong sign. If the igniter glows, and you hear the gas valve click but no flame, the issue is likely gas flow or burner cleanliness, not the igniter itself.
What a technician does that makes the difference
A seasoned tech in gas furnace repair Denver work approaches ignition failures with a meter, manometer, and a feel for patterns by brand and age. The workflow typically includes measuring voltage to the igniter during the call for heat. For silicon carbide igniters, resistance testing can indicate health. Silicon nitride igniters behave differently and often require only visual inspection plus live voltage checks.
The tech will verify manifold pressure with a manometer, usually around 3.5 inches water column at sea level for natural gas, adjusted for altitude. In Denver, slightly lower pressure or a different orifice size is common due to derating. If pressure is correct and the igniter glows, focus moves to burner alignment, carryover ports, and gas valve timing.
Draft and condensation issues get attention because a blocked condensate trap or a sagging exhaust line can slow the sequence and trigger faults misattributed to the igniter. A quick check of the pressure switch tubing and port often uncovers the real cause.
Finally, the tech cleans the flame sensor, which is just a metal rod in the flame path. A pad of fine steel wool or emery cloth takes off oxidation. If the furnace lights then fails flame prove, that simple cleaning can restore operation.
Common igniter types and what Denver homeowners see
Two families dominate:
Silicon carbide igniters are the old veterans. They glow bright orange, heat fast, and are more fragile. Typical lifespan ranges from 3 to 7 years in steady use, shorter with cycling stress. If you remove one, it might show tiny cracks or a pitted surface. Early 2000s furnaces often carry these.
Silicon nitride igniters are tougher, sometimes shaped like a little paddle or a U. They run cooler, tolerate more cycles, and last longer. They do not always look as bright when glowing. Many replacements upgrade older furnaces to nitride, but the bracket and connector have to match. Some boards need a small wiring change or a substitute kit. A mismatch can cause delayed ignition or premature failure.
Altitude-rated kits exist, not for the igniter itself but for the broader combustion setup. Newer igniter-control modules time the glow differently at elevation to allow reliable light-off with leaner mixtures.
The hidden causes behind repeated igniter failures
If you’ve replaced an igniter twice in a few seasons, step back. There’s usually a root cause.
High incoming voltage can overheat an igniter. A simple test with a multimeter at the furnace line voltage tells you if you’re outside the typical 114 to 126 VAC range. Surge events can also nick electronics and shorten igniter life. An inexpensive whole-home surge protector at the panel can help.
Dirty burners create uneven ignition. The igniter glows, gas opens, but the flame front does not cross properly. Heat builds near the igniter tip and the element fails early. Pulling and cleaning burners is not hard for a pro but takes care to re-seat and align.
Improper gap or misalignment between igniter and burner can waste heat. If the replacement was forced, or the bracket is bent, the element will glow without kissing the gas stream directly, which overheats the element and slows ignition.
Short cycling wears everything. Oversized furnaces common in older Denver bungalows run for 3 to 5 minutes then shut off. The igniter sees more on-off cycles per hour than intended, cutting lifespan. Adding a better thermostat with cycle rate control, improving ductwork, or tuning fan speeds can mitigate.
Condensate or venting issues in high-efficiency furnaces add their own trouble. In freezing weather, a partially blocked intake or a trap with sludge delays draft proving, then restarts. Each aborted attempt counts as a cycle against the igniter.
Telling the difference between a $50 part and a bigger decision
When the furnace is 15 to 20 years old, every repair is a question. Spending on repeated igniters, pressure switches, and control boards within a year can exceed the value of a planned upgrade. With fuel costs and comfort in mind, Denver homeowners often weigh furnace replacement Denver options after a winter of nuisance lockouts.
I encourage people to look at the combined picture. If the heat exchanger is sound and efficiency is decent, targeted repairs and a thorough furnace tune up Denver service can buy years. If the unit shows corrosion, heavy rust at the burners, or repeated flame rollout trips, it is time to talk about furnace replacement Denver. Newer equipment manages ignition sequences more gently and handles altitude better when set up correctly.
The value of precise maintenance in the Mile High City
Generic maintenance checklists miss local conditions. A thorough furnace maintenance Denver visit should include burner removal and cleaning, inspection of the igniter and flame sensor with real measurements, vent and intake checks sized for altitude, verification of manifold pressures adjusted for 5,000 to 6,000 feet, and a static pressure check across the duct system. The last item matters, because poor airflow forces short cycles that punish ignition parts.
Combustion analysis with a calibrated analyzer helps. CO and O2 readings reveal lean or rich conditions invisible to the eye. If your tech carries a manometer and a combustion analyzer, you’re getting real service, not just a filter swap.
DIY replacement or call for service?
Replacing a hot surface igniter is mechanically simple on many models: shut off power and gas, remove a screw, unplug the connector, avoid touching the element, and reverse the process with a matching part. The risk is in the details. A wrong part can fit but draw too much current and shorten board life. An igniter installed too close to the burner port can crack on first light-off. If the wiring harness is brittle, moving it can break a conductor inside the insulation, leading to intermittent faults that are maddening to trace.
I’ve seen homeowners do a flawless swap and restore heat quickly. I’ve also seen scorched wires and a cooked board from an igniter that shorted to the burner. If you try it, label everything, take photos before removal, and use the exact OEM part or a proven cross-reference kit. If your furnace is under warranty, remember that self-installed parts can void coverage.
What a proper igniter replacement looks like
For those who want the play-by-play, here is a clean sequence that minimizes risk and avoids rework.
- Kill power at the furnace switch and breaker, and shut off the gas cock if your model places the igniter near gas fittings. Remove the burner compartment door. Verify zero voltage with a non-contact tester at the board before touching wires. Photograph the existing igniter from multiple angles. Note wire routing and the gap between the igniter tip and burner port. Remove the mounting screw, cradle the bracket, and unplug the connector without pulling the wires. Handle the new igniter only by the ceramic or the connector. If it’s silicon carbide, do not touch the gray element. If you do, clean with alcohol and let it dry. Install using the original bracket and hardware. Align it so the element sits in the gas stream where the old one did. Inspect nearby wires and the flame sensor. If the sensor is dull or sooty, clean it gently. Re-seat all quick connects on the limit switches and the gas valve. Vacuum light dust but do not blow compressed air into the cabinet, which spreads soot into the heat exchanger. Restore power and run a heat call. Watch the full sequence through burner light-off and blower start. Check for smooth ignition in under 3 seconds. If ignition is delayed or rough, shut down and reassess alignment and burner cleanliness before repeated cycles.
This level of care reduces early failures and avoids the domino effect of burned connectors and lockout codes.
When igniter failure signals a control board problem
Every so often, the igniter tests fine, but the board doesn’t send power. I see this on units where a past surge hit the board, leaving half the relays weak. The board might drive the inducer and open the gas valve, then stumble on the igniter output. Testing live voltage to the igniter during the call is definitive. If you never see the expected 120 VAC (or the specified low voltage on some nitride systems), the board is suspect.
Another tell: the igniter glows and the gas valve opens, then closes quickly, with no flame. The board’s timing may be off or its flame sense circuit unstable. Before replacing a board, rule out poor neutral or ground connections. A loose ground back to the service panel can mimic a bad board by confusing flame sensing. In older Denver homes with knob-and-tube remnants or bootleg neutrals, I’ve solved “bad board” symptoms by fixing wiring.
Gas supply issues that masquerade as igniter failures
During cold snaps, gas demand spikes. If multiple homes on a line pull hard, marginal regulators show their age and manifold pressure sags. The igniter does its job, but the flame won’t cross properly. Watch for a faint whoosh followed by a dropout and retry. In these cases, a manometer reading during ignition tells the truth. Your furnace might be fine, but the supply does not hold. Utilities usually respond quickly to documented low pressure calls, especially during extended cold.
Inside the home, flexible gas connectors can kink when a furnace is moved for cleaning. Orifices collect debris. Spiders love burner tubes. Each of these narrows flow and causes delayed ignition that cooks igniters.
The altitude setup many furnaces never got
I still find furnaces installed without proper high-altitude adjustment. At 5,000 to 5,500 feet, many models require smaller orifices or a revised pressure setting. Some need a specific dip switch configuration on the control board for igniter warm-up time. If your furnace has always lit hard or boomed slightly on ignition, it may be set for sea level. During a furnace service Denver appointment, ask for confirmation of altitude settings, not just a generic check. It’s a small job with outsized payoff in reliability and igniter life.
Planning ahead with maintenance instead of midnight calls
The best time to solve ignition problems is October, not January. A targeted furnace tune up Denver visit should include opening the burner compartment, cleaning and aligning burners, measuring ignition timing, checking flame rectification microamps, cleaning the flame sensor, verifying igniter amperage draw against spec, and logging manifold pressure under load. Those five to seven measurements turn a reactive repair into a stable heating season.
Pair that with simple homeowner habits: change filters on schedule, keep storage boxes off the furnace, and avoid painting or staining inside the home without extra ventilation, since airborne solvents can form conductive films on sensors and igniters.
When it’s time for a new system
If a furnace is past 18 years and ignition issues come back every season, consider Furnace Replacement Denver CO options. A new 95 percent AFUE unit with modulating gas valves handles light-off more gently, which protects igniters. Set up correctly for altitude, these systems start cleanly in two seconds or less and rarely cycle on safety. Noise drops as well, because there’s no boom or rumble from delayed ignition.
A responsible contractor will give a load calculation for sizing, confirm venting paths in older homes with tight alleys, and outline choices for filtration that keep dust off ignition components. If your ductwork is undersized, discuss fixes now. An undersized return can ruin even the best Furnace Installation Denver CO job by forcing short cycles that beat up ignition parts.
For homeowners who plan to move within a few years, a mid-tier replacement may hit the sweet spot. For a forever home, a variable-speed, ECM blower with a matching thermostat can stretch igniter life by reducing on-off cycles and smoothing combustion.
A word about warranties and parts quality
Not all igniters are equal. OEM parts cost more but match the heat-up curve your board expects. Universal kits work when matched correctly, but I’ve seen cheap imports glow slow, causing repeated retries. If your furnace is under parts warranty, require OEM. If you go universal, pick brands with documented amperage and warm-up times and use the correct bracket. Keep the packaging and part number for future reference.
Labor warranties vary. A reputable provider of furnace service Denver work will cover their igniter replacement for a year on workmanship. Parts warranties depend on the furnace manufacturer and whether the product is registered. If a company balks at documenting measurements taken during the visit, that’s a sign to keep looking.
Realistic costs and timelines
In Denver, a straightforward igniter replacement often runs in the low hundreds for parts and labor during regular hours, rising for after-hours emergency calls. If the visit includes burner cleaning, flame sensor service, and combustion checks, budget a bit more but expect better results. A control board replacement pushes the cost higher, and any venting or condensate repairs add time.
Plan on 30 to 90 minutes for a clean igniter replacement when parts are on the truck. If a technician needs to source a brand-specific part, same-day is still common, but snowstorms stretch supply lines. Good companies keep common igniters for the popular brands found across Denver’s subdivisions and older neighborhoods.
Choosing a service partner you can trust
Cool marketing doesn’t fix heat. Look for a company with documented training, altitude-savvy technicians, and test equipment in every truck. Ask if their furnace maintenance Denver program includes combustion analysis and written readings. If the answer is a vague checklist without numbers, keep calling.
For immediate no-heat calls, describe the symptoms clearly. Share any error codes and what you’ve already tried. Mention the furnace brand and approximate age. If you’ve had repeated igniter failures, ask for a lead tech with experience in your model. Professionals appreciate precise information, and you get faster, better work.
Final thoughts from the field
Igniter failures feel arbitrary until you see the pattern: dry air, dust, altitude, voltage, and cycling. Tackle those and the little ceramic workhorse lasts longer. Pay attention to the whole ignition sequence, not just the glowing part at center stage. With the right setup and a bit of measured care, you’ll cut down on emergency visits and glide through the cold snaps that make Denver winters beautiful from the window and not from under a blanket.
If you need help now, look for gas furnace repair Denver specialists who test before they guess. If you’re planning ahead, a fall furnace maintenance Denver appointment can uncover the small issues before the first freeze. And if your old unit coughs through another January, it might be time to talk seriously about Furnace Replacement Denver CO and a proper Furnace Installation Denver CO that respects altitude and airflow from day one.
Tipping Hat Plumbing, Heating and Electric
Address: 1395 S Platte River Dr, Denver, CO 80223
Phone: (303) 222-4289